Frequency converter tube



June 3, 1958 F. T. QUIGLEY ETAL FREQUENCY CONVERTER TUBE 2 Sheets-Sheet 1 Filed Jan. 17, 1955 gi/263i; OUIGLEY ATTORNEY? J. BISSU INVENTORS ROBERT June 3, 1958v Filed Jan. 17, 1955 T. QUIGLEY ETAL 2 Sheets-Sheet 2 Apag.5

INVENTOR ROBERT J. BLS 0 RANG/S T. QUIGLEY m/d ATTORNEY tlnited dentes FREQUENCY CNVERTER TUBE Application January 17, 1955,' Serial No. 482,624

Claims. (CL S13- 69) This invention relates to frequency converter tubes of the types 'employed in radio equipment to convert an incoming signal at any frequency into a signal at a fixed frequency by electron interaction of the incoming signal with electrons at a selected frequency created by a local oscillator.

In such tubes, the local oscillator is usually comprised of a cathode, a local oscillator grid which is Wire wound and an anode. rfhis anode may be in the form of a wire wound grid structure. The signalvcontrolled portion of the tube comprises a virtual cathode formed outside the previously referred to anode, a second control grid beyond the virtual cathode, a screen grid electrically connected to the said anode, and a second anode in the form of a non-perforate plate. Between the second anode and the screen grid; is a coarse screen suppressor grid which may be connectedto the emissive cathode to there- `by prevent secondary emission from the second anode and which except for the suppressor would couple the input and output of the signal section and thereby cause oscillations and` other undesired effects. Thus the tube described, known as a pentagrid converter, involves, besides the emissive cathode and the imperforate anode, the use of five different grids.

It is an object of this invention to improve the performance of a tube having the described function.

lt is a further object of the invention to produce a converter tube with a fewer number of grids than heretofore thereby enabling simpler assembly of the tube.

lt is a still further object of the invention to make parts of such shape and size, as to reduce internal noise and interelectrode capacitance.

It is yet another object of the invention to so construct the tube as to minimize possibility of movement of parts of the tube with respect to one another.

These and other objects will be more clearly perceived after reading the following specification when taken in conjunction with the accompanying drawing in which:

Fig. l is a top plan view of a tube embodying my invention, the envelope being shown in section.

Fig. 2 is a vertical elevation of the tube with the en` velope and a shield partly broken away to expose the inner electrode.

Fig. 3 Ais a section on the line 3-3 of Fig. 2.

Fig. 4 is a view similar to Fig. 2 but at right angles thereto. p

Fig. 5 is a perspective view of the mount within the tube of Figs. l to 4, with parts broken away.

Considering the drawings in greater detail, there is shown as mounted between a pair of insulating wafers llt?, an indirectly heated cathode l2, the cathode being of the type conventionally employed in the art. Also supported between these wafers and in telescoped relationship to one another is a lirst wire wound grid 14 and a second wire wound grid i6, the side rods 17 of which are visible above the wafer in Fig. 5.

To each of the side rods i7 of the grid 16 and extending along a rod from one insulating wafer to the "Patented June 3, 1958 Ygrid 16, but ay gap is provided between the plates of a width approximately equal to the width of the cathode the gap. Opposed to the openings between the plates is a pair `of'half grids 26 of arcuate shape with the concave faces of the grids facing away from the cathode. yPositioned opposite each of the concaved faces ofthe grids is a pair of accelerating electrodes or rods 22, these rods being slightly less spaced apart than the spacing between the support rods `of its associated arcuate grid Ztl. Next in order is a pair of anodev plates 24, one opposite each concaved face of an arcuate grid, with the rodsZ-Z, between an arcuate grid and an'anode plate. Surrounding the electrode assembly is a shield 34, not shown in Fig. 5. The grid 12d is so shaped that electrons passing through the grid will be converged onto the plate, straying of electrons being prevented by positive po ential imposed on the rods 22. The rods also effect reduction in capacitance between the arcuate grid andthe plate. The plate, because of thebearn converging effect of the concave second control grid and rods 22 can be and is made of narrowwidth only slightly wider than the spacing apart of the accelerator rods, therebymaking it possible to have small capacitances to the plate. Suppression of emission of secondary electrons from the plate is obtained by the converging of the electron stream by the arcuate ygrid into a narrow beam so that a region of high density, forming a virtual suppressorjo-ccurs in front of the plate. The increased density of electrons in front of the plate lowers thespace potential sufficiently tov prevent the emission of secondary electrons from the plate thereby avoiding the necessity of providing a suppressor grid.

Each of the parts previousiy described is held in position by the two insulating wafers it). The cathode sleeve, as is customary in the art, may have a single bead near one end thereof to rest on the lower wafer, the upper end being free to expand and contract through the upper wafer; the grids id, i6, and Ztl have grid side rods suitably held to the wafers as by slight deformation of the protruding ends. The imperforate anodes 24.1 have reduced in width ends 26 of less width than the anode portions between the wafers, these ends extending through suitable slots in the insulating wafers. At one end of the mount, preferabiy at the upper end, the two arcuate grids 2Q are electrically connected by a straight bar 23 bearing against the upper surface of the upper wafer and welded to the grid side rods. The rods 22 are connected in pairs by U-shaped rods 30 integral with the rods 22. The rods 22 are at the same electrical potential as the grid t6, being electrically joined to the side rods of the grid. The two anode sections are'electrically Vjoined by the U-shaped strap 32, the legs of which are welded to the anodes and abut the upper surface of the upper wafer. Thus the bars and straps not only serve to electrically connect pairs of elements of like character but also act as stops to rigidity the entire structure. rhe mount, as is customary in the art, is enclosed with an envelope 36 from which the air has been exhausted.

What is claimed is:

l. A frequency converter tube comprising an oscillator section including a cathode, a rst control grid and a rst anode; an incoming signal section comprising a second control grid, a second anode and accelerator means between said second control grid and second anode, said first anode lying between said first control grid and said second grid, said second control grid being arcuate in form with the concave side facing the 3 second anode and said accelerator means being a pair of rods spaced apart substantially the width of the second control grid and opposite the lateral sides of the second control grid.

2. A frequency converter tube comprising an oscillator section including a cathode, a control grid and an anode; an incoming signal section comprising a second control grid, a second anode and accelerator means between said second control grid and second anode, said second control grid being arcuate in form with the concave side facing the second anode and said accelerator means being a pair of rods spaced apart substantially the Width of the second control grid and opposite the lateral sides of the second control grid, the second anode being a plate of a width only slightly wider than the spacing of the accelerator rods from each other.

3. A frequency converter tube comprising a pair of insulating wafers and a number of electrodes supported therebetween, said electrodes comprising a cathode, a first grid surrounding the cathode, a second grid surroundingV the irst grid, a pair of half grids having side rods and grid laterals secured to the side rods, said half grids lying on diametrically opposite sides of said second grid and each half grid being arcuate in form With the convex side directed toward the cathode, a pair of accelerator rods opposite the concave side of each half grid with a rod opposite each side rod of said half grids, an anode plate opposite each pair of side rods on the sides of the rods away from the half grids, each of said grid, accelerator rods and anode plates extending above one of said insulating wafers, and a tie bar above the said one wafer connecting the anode plates together, the accelerator rods opposite one of said plates being connected by rods above the same wafer to the accelerator rods opposite the other of said plates, said connecting rods also being secured to the second grid.

4. A frequency converter tube comprising a pair of insulating wafers and a number of electrodes supported therebetween, said electrodes comprising a cathode, a rst grid surrounding the cathode, a second grid surrounding the first grid, a pair of half grids having side rods and grid laterals secured to the side rods, said half grids lying on diametrically opposite sides of said second grid and each half grid being arcuate in form with the convex side directed toward the cathode, a pair of accelerator rods opposite the concave side of each half grid with a rod opposite each side rod of said half grids, an anode plate opposite each pair of side rods on the sides of the rods away from the half grids, each of said grids, accelerator rods and anode plates extending above of said insulating wafers, a tie bar above the said one wafer connecting the anode plates together, the accelerator rods opposite one of said plates being connected by rods above the same Wafer to the accelerator rods opposite the other of said plates, said connecting rods also being secured to the second grid, and a bar above the said one wafer connecting the two half grids together.

5. A frequency converter tube comprising an oscillator section including a cathode, a first control grid and an anode; a iirst incoming signal section comprising a second control grid, a second anode and accelerator means between said second control grid and second anode, said first anode lying between said rst control grid and said second grid, said second control grid being arcuate in form with the concave side facing the second anode and said accelerator means being a pair of rods spaced apart substantially the width of the'second control grid and opposite the lateral sides of the second control grid, the second anode being a plate of a width only slightly wider than the spacing of the accelerator rods from each other.

References Cited in the file of this patent UNITED STATES PATENTS 2,Q97,306 Rothe et al. Oct. 26, 1937 2,146,016 Herold s Feb. 7, 1939 2,573,397 Burnside Oct. 30, 1951 FOREIGN PATENTS 518,898 Great Britain Mar. 11, 1940 

